嬰兒食物過敏的原因：一、嬰兒腸道屏障功能不完善，小嬰兒腸道發育不成熟，有一些食物顆粒，如牛奶蛋白分子，很容易透過這一屏障，從腸腔進入血液導致過敏，二、免疫系統發育不成熟，由於小嬰兒的免疫系統發育不平衡，天生容易向引起過敏的方向傾斜，一旦受到牛奶，雞蛋等大分子異性食物蛋白的刺激就容易出現過敏表現。三、遺傳因素。如果爸爸媽媽雙方都有過敏史，嬰兒發生過敏的機率就很大。四、新增輔食貪多貪快。小嬰兒腸胃功能發育不全，如果新增輔食的種類過多，新增的時間較早，也容易導致嬰兒過敏。如何預防嬰兒過敏：儘量延長母乳餵養的時間，因為母乳中含有多種對過敏有制約作用的免疫球蛋白及抗體，對防止過敏很有好處。當媽媽母乳不足或者無法母乳餵養的時要讓孩子儘早使用適度水解蛋白配方奶，以減少嬰兒對牛奶蛋白過敏的風險，再新增固體的食物的時候，要一次只新增一種，觀察幾天，如果嬰兒沒有不良反應，再新增另一種。

根據美國過敏、哮喘和免疫協會的建議，一，在寶寶1歲內新增最易過敏類食物有助於減低之後引發的食物過敏風險；二，新增輔食的品種從不易引起寶寶過敏反應的食物開始；三，為你的寶寶提供單一品種的輔食便於識別造成Ta過敏的過敏源。

以下翻譯文字來自：

https://www.babycenter.com/0_feeding-problems-food-allergy-in-babies_9204.bc

什麼是食物過敏？

食物過敏是人體免疫系統對某一特定食物產生的一種不正常的免疫反應。當過敏性體質的寶寶吃了過敏性食物，Ta的身體內就會產生抗體，釋放出其他物質，引發免疫系統的不正常反應。大約有5%的孩子會有食物過敏症。

如何減低引發孩子食物過敏的風險？

大概4~6個月時，大多數寶寶就可以吃固體輔食了，只要他們表露出這樣的意願。

每個寶寶是不同的，所以與你的兒科醫生討論新增輔食的品種及時機是一個好辦法。醫生會建議你從蔬菜泥、水果泥、肉泥或鐵強化燕麥片開始——這都是些基本上不易引起寶寶過敏反應的食物，但專家也建議要時刻觀察寶寶有無任何過敏反應，以防萬一。你的寶寶在嘗試過這些傳統的第一階段的輔食後，如果看上去有較好的適應性，你就可以給Ta新增過敏性輔食了。美國過敏、哮喘和免疫協會（American Academy of Allergy, Asthma, and Immunology）表示，在寶寶1歲內新增最易過敏類食物，比如堅果類、蛋類和魚類等有助於減低之後引發的食物過敏風險。

新增任何一種新的食物，都要堅持觀察3~5天后發現沒不良反應後再嘗試另一種食物。對食物的過敏症狀可能就出現在一段時間內。而且，為你的寶寶提供單一品種的輔食便於識別造成Ta過敏的過敏源。

（備註：不要在寶寶1歲前給Ta喂蜂蜜或牛奶。但含有乳蛋白類的食品——比如乳酪和酸奶——通常是可以作為輔食新增的。）

附英文原文如下：

Feeding Problems: Food Allergy in Babies

What is a food allergy?

A food allergy is the immune system"s overreaction to normally harmless proteins in a particular food. When a baby with an allergy eats an offending food, his body produces antibodies and releases other substances that cause the immune system to react. About 5 percent of children have food allergies.

Can I reduce my baby"s risk of developing a food allergy?

Possibly. Around 4 to 6 months, most babies can start to

eat solids

if they show signs of readiness.

Every baby is different, so it"s a good idea to talk with your child"s doctor about which solid foods to introduce and when. Her doctor may suggest that you start with pureed veggies, fruits, meats, or iron-fortified cereal – these typically don"t cause allergic reactions in babies, but experts recommend observing your baby for signs of an allergy, just in case.Once your baby has tried a few of these traditional first foods and seems to be tolerating them well, you can give her allergenic foods. Introducing highly allergenic foods such as nut products, eggs, and fish within your baby"s first year may help reduce your baby"s risk of developing food allergies later, according to the American Academy of Allergy, Asthma, and Immunology.

When introducing any new food, stick to it for about three to five days before trying the next food. Chances are the symptoms of a food allergy will show up within this time. Also, give your baby single-ingredient foods to make it easier to identify any she may be allergic to.

(Note: Don"t give your baby

honey

or

cow"s milk

before her first birthday. But products that contain processed milk protein – such as

cheese

and yogurt – are usually fine to include in your baby"s solid food diet.)